Apparatus for tying elastic threads



March 28, 1961 w. GEGENSCHATZ ETAL 2,977,144

APPARATUS FOR TYING ELASTIC THREADS Filed June 50, 1958 Inventors Martin Buchmann Waller Gegens chafz APPARATUS FOR TYING ELASTIC THREADS Walter Gegenschatz, Uster, Switzerland, and Martin Buchmann, Manchester, England, assignors to Zellweger A.G., Apparateund Maschinenfabriken Uster, Uster, Switzerland, a corporation of Switzerland Filed June '30, 1958, Ser. No. 745,717

Claims priority, application Switzerland July 6, 1957 2 Claims. (Cl. 289- 12) It is well known that innumerable mechanical devices have been utilized for the tying of threads and filaments. One of the major classes of thread tying devices relies for its action upon a sleeve arrangement, which may also comprise a plurality of'sleeves, around which the thread loops are formed and which also contains a retractable, reciprocating hook. After the loop formation, the retractable hook draws the ends of the threads into the interior of the, sleeve or sleeves so that on stripping the loops over the free end of the hook the desired knot is formed. For the desired loop formation, the sleeves and the clamps holding the ends of the threads must rotate relative to each other and this may be accomplished either by the rotation of the sleeve itself, which is provided with a hook operatively connected to the sleeve, or

by the rotation of the clamp holding the thread ends about the stationary sleeve. For the formation of loops, the length of thread requiredis provided in each case by permitting the thread ends frictionally engaged by the thread clamp to slide therein. The thread clamp is so designed that it is held in closed position, for example, by means of a spring. It may be opened either by the action of the thread itself or it may be so designed as to be held in closed position by the action of a spring and opened by suitable means of the tying machine. The latter design and arrangement of the thread clamp has nited States Patent usually served heretofore only to enable the threads to be inserted more easily since the threads, in each instance, after the completion of the knot-tying step are caused to slide free of the thread clamp.

When tying threads of a highly elastic material such as a cellulose-based yarn or the like spun around a rubber thread or monofilament, the above devices are quite impractical. Since the thread, in each instance, must be withdrawn from the thread clamp at the completion of the knot-tying operation, the pressure exerted by the thread clamp should not be excessive. In such a situation, however, if the elastic yarns are drawn from the thread clamp against the tension which the elastic yarns exert and before the retractable hook has drawn the yarn ends into the sleeve, it is apparent that in the ordinary situation a knot will not be formed since once the ends of the elastic thread are drawn out of and leave the thread clamp they will, because of the tension they are under, immediately snap away from the sleeve. 7

It is, therefore, an important object of this invention to provide a device for the knotting of highly elastic threads utilizing a sleeve about which the desired loops are formed but which will not be subject to the disadvantages of the devices hitherto available.

Another object of this invention is the provision of a knot-tying device for the knotting of elastic threads in which the threads are gripped firmly during the operation to prevent slippage but are then released in a suitably timed sequence of operations in order to enable the thread ends to be drawn into the actual knot-tying operation.

following detailed description.

In the drawing Fig. 1 is a perspective view, partly in section, of the knot-tying device of this invention showing the sleeve about which the threads are wound to form the loops, the retractable hook which effects the actual knotting of the threads as well as the thread clamp in which the threads are gripped as the operation is effected, and

Fig. 2 is a diagram of the rotational timing sequence of the device shown in Fig. 1.

Like numerals indicate like partsthroughout the several views of the drawing. i

Referring now to the drawing, and more particularly to Fig. 1, reference numeral 1 identifies a fixed sleeve of the type commonly employed for the tying of threads the interior of which is providedwith a hook 2 which is reciprocatably mounted within sleeve 1 for extended lateral movement axially thereof and is actuated in said movement by a suitable mechanism (not shown). A key 3 is mounted in a suitable keyway provided in a' hollow shaft4 which in operation rotatesin the direction of the arrowand which is so timed that it m'akesthree complete revolutions over the course of each knot-tying operation. Keyed to shaftv 4 and rotating therewithby reason of key 3 is a pinion gear 5 whose boss 6 carries a radial flange 7 which, together with pinion gear 5 encloses the arm of a bracket 9, the arrangement of the several parts being such that together with bracket 9 pinion gear 5 and flange 7 can be shifted or displaced laterally in a direction along the axis of hollow shaft 4. This lateral movement is effected by means of the action of rod 10 which is operatively connected to bracket 9, the desired movement of rod 10 in the direction indicated being produced by suitable actuating means (not shown);

Mounted onbracket 9 are a pair of rotatably mounted gears 11 and 12 which are fixed to the same shaft (not shown), the relationship being such that gear 11 meshes with gear 5 and gear 12 meshes with a gear 13 whichis mounted on boss 6 and which is freely rotatable relative thereto. The respective gear ratios of the several gears 5, 11, 12 and 13 are such that three full revolutions of gear 5 cause gear 13 to rotate once about its axis. Gear 13 is fixed or aligned in the desired relative axial position on boss 6 by means of its boss 14 which abuts against an annular collar 16 held in position on boss 6 by means of an adjustable set screw 15. Fixed to the circum: ference of annular collar 16 is a tube 17 which is thus rotatably mounted relative to the sleeve 1. The end 18 of the tube 17 forms a fixed or stationary arm or jaw of a thread clamp mechanism. The opposing jaw of the thread. clamping mechanism is the movable clamping arm or jaw 19 which is held in position on the end of a shaft 20 by a screw, as shown. Shaft 20-carries a collar 21 at the opposite. end thereof against which is pressed a coil pressure spring 22 which acts not'only to forcebut to maintain the clamping arm or jaw 19 in spring-loaded contact with the fixed or stationary clamping arm or jaw 18.

During the rotation of gear13 theotfset lug 23, which is integrally formed with said gear 13, comes into contact with the end of shaft 20 and by reason of its shape exerts ,a camming action clue to the increasing pressure of said offset lug 23 thereon thus causing shaft 20 to be moved in a direction against the pressure of the spring 22 thus causing movable clamping jaw 19 to move away from contact with fixed clamping jaw 18. As brought out in greater detail below, this action takes place twice during each knottying operation.

Furthermore, as indicated by the above gear ratios, gear 13 rotates only once for every three revolutions of gear 5. Accordingly, since the thread clamping mechanism is mounted on collar 16 which rotates at the same radial speed as gear 5, being fixedly mounted on boss 6 by means of set screw 15, the thread clamping mecha nism will likewise rotate three times for each rotation of gear 13. The lug or cam 23 is so designed that over 40 of revolution of gear 13 it is able to maintain the thread clamping mechanism in open position, but the actual contact of cam 23 with the end of shaft 20 occurs over only 30 of revolution because of relative displacement of the respective parts. During this movement the thread clamping mechanism itself rotates from its initial position at 30 to a position at 90 of revolution so that the net movement of the cam 23 on gear 13 is actually over only 20 of revolution, even though the thread clamp is at the 90' position.

The net elfect of the relative movements involved is that the jaws of the thread clamping mechanism remain open while it rotates from the 30 to the 90 position and the jaws then close. As the thread clamping mechanism moves from the 90 position to the 360 position and on the second revolution around to 570, the cam 23 radially advances meanwhile over a net of 160 so that its position is at 250", its action thus beginning at 210 or at 570 as the case may be. In this position the filament clamping mechanism is opened and remains open, as previously indicated, for 60 of revolution. Thereafter, the thread clamping mechanism advances relative to the cam 23 so that during the third revolution it remains closed. After the mechanism has rotated through 1080 the knot-tying operation has been completed and a new cycle commences. The relationship of the relative rotational movements are graphically illustrated in Fig. 2 wherein the three revolutions of the thread clamp are represented by three concentric circles on which are indicated the respective degrees of revolution of the elements involved. The heavy line represents the period during which the thread clamping mechanism remains open.

It is readily understood that by a suitable choice or proportion of cam length and by a suitable variation of its position relative to the rotating thread clamp at the commencement of the knotting operation, one can vary within limits the duration of the period during which the thread clamp remains open and the period during which it is closed, so that the knotting operation can be very accurately adjusted. The particular relationships of the several elements given above with respect to their relative rotational movement are merely given by way of illustra'tion and in no way are to be considered as limiting the claims.

As an example of the manner in which the device of the present invention operates the following detailed example and description is given:

By suitable means (not shown) the pair of threads to be knotted are brought into the path of the thread clamp which, as described above, is maintained in open position when rotating from 30 to 90 and then closes as it reaches 90 of rotation. The force exerted by the coil spring 2 2, when the clamping mechanism is in closed position, is sufficient so that the elastic threads are unable to be withdrawn from the thread clamp at any time. The firm grip of the clamp on the elastic threads can be ensured by roughening the faces of the clamping elements or jaws or by providing the clamping elements with conventional serrations or teeth which will mesh and will thereby exert a maximum holding force on the threads. The initial revolution of gear 13 causes the thread clamp assembly which is carried on collar 16 to place a loop of the paired threads about the stationary sleeve 1. During the second complete revolution the free ends of the threads forming the loop, by virtue of the timed axial displacement of the thread clamp assembly by suitable movement of the rod 10 is carried over the free end of sleeve 1 and is placed in the book 2. Just as soon as the threads have been placed in hook 2 it is caused to be retracted by means of the actuating mechanism provided in the sleeve and the movable thread clamping arm or jaw 19 is moved out of contact with the stationary clamping arm or jaw 18 thus freeing the thread ends gripped by said jaws immediately. The above operation is, of course, continuously repeated.

The present invention is not limited to the particular embodiment disclosed above in which the thread or filament clamp rotates about a stationary sleeve.

What is claimed is:

1. In a device for knotting together the ends of a pair of threads including a sleeve around which said thread ends are looped and a reciprocating, retractable hook within said sleeve for drawing the thread ends through the loop and forming said knot, the combination of thread gripping means mouted on and integral with a circumferential collar rotatably mounted on said sleeve, said collar being provided with circumferential coaxial drive means producing rotation of said collar about said sleeve whereby thread endsgripped thereby are looped about said sleeve, said thread gripping means on said collar comprising a fixed jaw and a movable jaw carried on a laterally displaceable spring-pressed shaft, and means including a rotating cam in contact with said shaft operating in timed relationship to the reciprocating movement of said hook for permitting said thread gripping means to remain in spring-pressed closed thread gripping position during said knotting operation and for opening said thread gripping means at the completion of said knotting operation.

2. In a device for knotting together the ends of a pair of threads including a sleeve around which said thread ends are looped and a reciprocating, retractable hook within said sleeve for drawing the thread ends through the loop and forming said knot, the combination of thread gripping means mounted on and integral with a circumferential collar rotatably mounted on said sleeve, said collar being provided with circumferential coaxial drive means producing rotation of said collar about said sleeve whereby thread ends gripped thereby are looped about said sleeve, said thread gripping means on said collar comprising a fixed jaw and a movable jaw, a shaft carrying said movable jaw mounted thereon and a spring on said shaft normally maintaining said jaws in spring-pressed contact, and timing means including a face cam in contact with said shaft rotatably driven at a predetermined speed of rotation relative to the rotation of said thread gripping means so as to permit said thread gripping means to remain in spring-pressed closed thread gripping position during said knotting operation and to cause said thread gripping means to open at the completion of said knotting operation.

References Cited in the file of this patent UNITED STATES PATENTS 238,302 Ogden Mar. 1, 1881 238,327 Angspurger Mar. 1. 1881 266,958 Gordon Oct. 31, 1882 1,099,128 Poege June 2, 1914 2,678,229 Snortland May 11, 1954 

